Which of the following sequences diverges?
an=(−1)na_n = (-1)^nan=(−1)n
an=(−1)nna_n = \frac{(-1)^n}{n}an=n(−1)n
an=1n2a_n = \frac{1}{n^2}an=n21
an=sinnna_n = \frac{\sin n}{n}an=nsinn